Toll-trunk circuit.



C. S. WINSTON.

TOLL TRUNK CIRCUIT.

APPLICATION FILED FEB.2I. 1913.

1,203,959. Patented Nov. 7, 1916.

M5555: 5 V 1 Zia/527232;

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S Parana CHARLES S. WINSTON, OF CHICAGO, ILLINOIS, ASSIGNOR T KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TOLL-TRUNK CIRCUIT.

Specification of Letters Patent.

Patented Nov. 7, 1916.

Application filed. February 21, 1913. Serial N 0. 749,830.

T 0 all whom 2'25 may concern:

Be it known that I, GHARLEs S. WINSTON, a citizen of the United States of America, residing in Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Toll-Trunk Circuits, of which the following is a specification.

My invention relates to universal toll trunks, that is toll trunks used for extending connection from an operators cord circuit, such as a toll operators cord circuit, to telephone lines of various characters, local battery or magneto, and common battery lines.

i111 object of my invention is to provide a universal toll trunk of this character having simple and positive circuit arrangements, the new features thereof being more particularly referred to in the ensuing specification and claims.

In the accompanying drawing I have illustrated a telephone exchange system including the trunk circuit of my invention,

the system illustrated being the preferred arrangement.

The system shown is adapted for interconnecting telephone lines such as magneto lines A, which terminate in jacks 16 at an operators position, and lines terminating at a different operators position such as lines B and C. It is to be understood that there are a number of lines as A terminating at an operators position equipped with cord circuits D for interconnecting these lines while the distant operators position is equipped with suitable cord circuits for interconnecting acks as J .and J which are the terminals of lines B and C. l/Vhen conncction is desired between the lines of these different positions, the universal toll trunk E is used.

Referring now more in detail to the apparatus and circuit arangements employed, the line A. connects the magneto substation F with the jack 16, a. line drop 1 being connected to said line and adapted to be operated when a. call is initiated from the telephone F.

The cord circuit D which is used for interconnecting the lines A, is of a simple bridged drop clearing out type having an answering plug 2, and calling plug 3 connected by .conductors 4, 5, having a clearing out ,drop 6 connected in bridge thereof, A

listening key 7 is provided for connecting the operators set 8 to the cord, and a ringmg key 9 is provided for connecting the ringing generator in circuit. For convenience we shall refer to the operator that controls cord circuit D as the toll or originating operator.

Now as to the lines terminating at the distant operators position, these lines are of different characters and are known as local or magneto lines, and common battery lines C and B respectively. The line C connects a magneto substation telephone G to a line circuit H at the central oliice which line circuit comprises a cut-off relay CO, line relay LR, line signal LS and multiply connected line jacks J.

Line B which is the common battery type, connects a well-known form of common battery substation telephone K to the line circuit H at the central office, which line circuit comprises apparatus similar to that of line circuit H except that it is differently connected. The cut-off relays CO and C0 are of the convertible type and preferably have two windings, these windings being connected in series in relay CO so as to provide a high resistance path while these wind ings are connected in multiple in CO so as to provide a low resistance path.

Now as to the universal toll trunk IE, it comprises an out-going terminal preferably in the form of an out jack OJ, connected by strands 10, 11, to an incoming terminal preferably in the form of a plug P which is positioned before a toll trunk operator having access to the lines C and B. A disconnect signal relay DSR is connected to the out terminal OJ and is adapted to be energized when connection is made to this terminal, and subsequently dcenergized upon disconnection, to effect the lighting of the trunk disconnect signal TR which is positioned before the toll trunk operator and associated with its plug P.

It might be well to mention at this time that all of the ringing of the called line is controlled by the toll or originating operator, that is the toll operator of cord D, preferably using the ringing generator 15 connected to the ringing key 9 of the toll operators cord circuit.

As already referred to the universal cord circuit E is adapted to connect with either the common battery line or a local or magneto line as C and I have provided a pair of relays S t V and SR connected to the third cont-act of plug P. The switching relay SW is preferably of a higher resistance than the sleeve relay SR, and when connection is made to a magneto line in which the circuit to the cut-off relay is of a high resistance, relay SR energizes but relay 'SiV remains inert. But when connection is made to a common battery line as B in which a low resistance path is provided through the cut-oil relay CO both relays SR and SW operate. Although relay SW is of a higher resistance than relay SR, it does'not energizc in series with the cut-off relay CO due to its adjustment and the amount of work it has to perform. The relay SlV has several sets of contacts to operate while the relay SR has only one set of contacts to operate. Therefore the relay SW is wound to a higher resistance than the relay SR so that the best operation of these relays may be secured under the different operating conditions. Thus when connection is made with a common battery line the switching relay SYV operates to connect the bridging relay BB in circuit with the called line which relay serves to feed talking battery to the called line and also acts as a ringing dis-' connect and supervisory relay. Due to the fact that relay BB is connected in bridge of cord circuit B when a common battery line is connected with, means are provided for cutting this relay out of circuit while the ringing curr nt is being applied, and to this end the ringing relay RE- is adapted to operate the bridge cutoff relay BCU while the ringing current is on. Also due to the fact that circuit E is universal, inductive devices are provided in the form of condense-rs 1.3, 14 which condensers need re main in effective circuit only when connection is made between the magneto line as A. and common battery line as B. Therefore these condensers are short circuited by the shunting relay S when connection exists between two magneto lines as A and C. I also provide means whereby the shunting relay S may be energized to shunt the condensers l3, 14, when ringing current is being applied while connection is made to a common battery line as B, and to this end the relay S is adapted to be energized to shunt condensers 13, 14, whenever the ringing relay ER is energized. I also preferably arrange tol]. trunk E so that ringing relay HR is cut out of circuit during a conversational connection to a common battery line so as to remove this bridge connection. Therefore a disconnect relay DR is provided which energizes when the called subscriber at a common battery substation as K responds.

Operation: Assuming now that the subscriber at substation F desires a connection with a magneto or local battery substation G, he operates the hand generator in the usual manner thereby throwing the drop 1. The toll operator thereupon inserts a plug 2 into the jack 16 and connects her telephone 8f in circuit by means of the listeningkey 7* and finding that a connection is desiredwith a line terminating at a distant switchboard,

communicates by means of an orderwire key tin reasons hereinbefore set forth. The closing of contacts 26 of SR closes a circuit for the lamp TO, lighting said lamp as'the usual guard signal. Therefore, upon insertion'of the plug 3 into the out jack OJ by-the toll operator, the contacts 18 of the jack are closed, energizing the disconnect signal re lay DSR, and by the interruption of normal contact 12, causes effacement of lamp TO.

The toll or originating operator after inserting the plug 8, listens to ascertain the condition of the called line, and finding it idle, operates the ringing key 9 in the usual manner to connect the ringing generator 15 in circuit with the'conductors 10, 11, of the trunk circuit and thus in connection with the called line C. This connection of ringing current operatesthe ringingrelay RR each time the key 9 is actuated this operating circuit being traced from generator 15, tip of plug 3 and jack OJ, conductor 10, normal contact 520, the winding of RR,"conductor 11 and the sleeve contacts of jack OJ and plug 3 to the grounded ringing key contact. 7 r

This operation of RR- when connection exists with a magneto line is only incidental and without effect as it will be remembered that relay ST? is not energized and therefore relay Bltis not in circuit. Also shunting relay S was energized when the plug P was inserted this having been brought about as follows: Upon said energization of relay SR, its alternate contact 26 closed establishing an operating circuit for the shunting relay S traced from said grounded contact 26, nori mal contact 23, and the winding of S to battery. Relay S therefore closed its alternate contacts 24:, to short circuit the condensers 13, 14c and thus establish a more effective ringing and talking circuit, as it will be remembered that two local substations are connected. Therefore when the toll operator throws the ringing key 9 to connect the ringing generator 15, the circuit for the ringing currentthrough substation marked conductors of the trunk circuit E.

and line circuit C, this ringing circuit being effective to operate the call bell at substation G which call bellis connected in bridge of the line conductor The subscriber at G removes his receiver in response to this signal and the two substations F and G are connected for conversation. After the subscribers have finished their conversation they replace their receivers upon their respective switch-hooks and operate their hand generators in the usual manner whereby the clearing out drop 6 of the cord circuit D operates in the usual manner. The toll operator observing the clearing out signal of the cord circuit D, withdraws plugs 2 and 3 from their respective jacks, the withdrawal of plug 3 causing the interruption of the circuit of disconnect signal relay DSR whereupon this relay restores establishing a circuit for the trunk operators disconnect sig nal TR. battery through normal contact 28 of relay DSR, lamp TR, to ground at alternate contact 2G. Lamp TR therefore lights indicating to the trunk operator that disconnection is desired and she withdraws plug P from jack J whereupon the circuit through relays SW and SR is interrupted causing the restoration of relay SR. Its alternate contact 26 is therefore interrupted interrupting the circuit for the relay S and the trunk lamp TR whereupon they are restored to normal. Trunk T is therefore available for use in establishing other connections.

Assuming now the subscriber at F desires connection with a common battery line as B, the assignment of a trunk E is the same as before but when the toll trunk operator inserts plug P into the jack J of the common battery line, thecut-off relay CO being of low resistance, sufficient current flows through relays SR and SW to cause the operation of both of them. The operation of SR lights lamp TO as before. Upon operation of SlV, its alternate contacts 29, 30, are closed connecting the bridging relay BR in bridge of the conductors 1.0, 11, of the trunk circuit. This circuit for relay BR may be traced from ground through the upper Winding thereof, normal contact 32, alternate contact and normal contact 24 to conductor 10 while the circuit through the other Winding may be traced from battery through said other winding, normal contact 34: and alternate contact 30 to conductor 11. This relay is of course in bridge of the line conductors of the called line B but due to the interposition of the condenser in circuit at the substation, the relay BR does not operate until the receiver thereat is removed. Although relay SR operates as before and its alternate contact 26 is closed, due to the fact This circuit may be traced from that normal contact 23 of the switching relay Si? is also interrupted, the closure of alternate contact 26 at this time does not operate the shunting relay S. The cut-off relay CO having operated its alternate contacts 36 37 are of course closed in the usual manner.

Ne w as to the ringing operation, after the to operator has inserted the plug 3 into the jar SJ, and relay DSR is operated to eiface lamp TO, the ringing key 9 is operated and thereby connects the generator 15 and ground to the conductors 10, 11. A circuit is hus established through the ringing relay as before causing its operation and the closing of its alternate contact 21 which effeet-E; the operation of the bridge cut-off relay ECO each time the ringing key is operated. The operation of relay BOO disconnects the bridging relay BR during the ringing period and also upon the closing of alternate contact 22 each time the relay BGO is operated, a circuit for relay S is established traced from said grounded contact 22, alternate contact 23, and the winding of S to battery. Relay S therefore closes its alternate conacts 24:, 25 to short circuit-the condensers 13, 14:, and thereby establish a more effective ringing circuit each time the ringing key 9 is operated.

The subscriber at substation K in response to the operation of the call bell thereat removes his receiver whereby a circuit for the lnfidging relay BB is established, traced from ground through the upper winding thereof, normal contact 32, alternate contact 33,norn1al contact 2st, conductor 10, the tip contacts of plug P and jack J alternate con tact 36 line conductors and substation K, alternate contact 37 sleeve contacts of the jack and plug, conductor 11, alternate contact 30, normal contact 34, and the lower winding of ER to battery. The relay BR therefore closes its alternate contact 39 establishing an operating circuit for the disconnectrelay DR which interrupts its normal contact 20 to interrupt the circuit for the ringing relay BR and by the closing of its alternate contact -.'l-O a locking circuit for DE is established to ground at alternate contact 26 so that relay DR cannot deenergize until the plug P is withdrawn. Also, responsive to the operation of relay BR, its normal contact 39 is interrupted thereby interrupting the circuit for the signal. TO whereby the toll operator knows that a response has been secured from the called substation.

After the subscribers have finished conversation, the subscriber at K replaces the reits jack whereupon relays SlV and SR restore, the restoration of relay SR causing the interruption of its alternate contact 26 and thereby the restoration of signal TR and relay DR while the restoration of switching relay SW disconnects the bridging relay BR from the trunk conductors. The restoration of the cut-oi relay CO restores the line circuit and thus the apparatus being at normal is available for use in establishing other connections. V

l Vhile l have illustrated and described a specific form of my invention, it is to be understood that many changes and modifications thereof may be made and I do'not desire to be limited to the exact structure as described but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

lVhat I claim as new and desire to secure by United States Letters Patent, is:

l. A telephonesystem comprising local battery or magneto and common battery telephone lines, line circuits of ditlerent character for said lines, a universal toll trunk for extending connection from a calling line to said lines, as called lines, a bridging battery supply relay, a switching relay adapted when operated to connect said bridging relay in bridge of the trunk circuit, a sleeve relay, means for energizing the switching relay and sleeve relay when connection is made to a common battery line and for energizing the sleeve relay but not the switching relay when connection is made witha local battery line, and a guard signal for said trunk circuit operated responsive to such operations of the sleeve relay.

2. A telephone system comprising local battery or magneto and common battery telephone lines, line circuits of diii'erent character for said lines, a universal toll trunk for extending connections from a calling line to said lines as called lines, outgoing ack terminals for said trunk circuit and incoming terminals for said trunk for connecting to said line circuits, a bridging battery supply relay, a switching relay and circuit connections whereby said bridging relay may be connected in bridge of the incoming end of the trunk circuit,-and means for energizing the switching relay when c0n- .nection is made to a common battery line ringing relay being operated by ringing cur-' rent when applied to the outgoing terminals oi? the trunk, and a shunting relay responsiiie to such operations of the ringing relay fer short circuiting said condensers when the ringing current is applied. 1

a; A ring through universal toll trunk comprising outgoing and incoming termi rials, conductors uniting said, terminals, C011: densers interposed in said. conductors, a ring relay in bridge oi. said conductors at the outgoingend thereof, said ringing relay bein operated by ringing current when applied to the outgoing terminals of the trunk, a shunting relay responsive to such operations of the ringing relay for short circuiting said condensers when the ringing current is applied so as to provide amore eli'ective ring-through circuit, a bridging relay adapted to'be connected in bridge of said conductors at the incoming end oi the trunk circuit, means for connecting the bridging relay in such bridged connection, a (ll-5C\')llnei3t relay having contacts included in the operating circuit of theringing relay, and means for operating the disconnect relay controlled by said bringing relay.

5. A telephone system comprising lines of dill'erent characters, a cord circuit for extending a calling line to a universal toll trunk circuit said toll trunk circuit extending the calling line to the called lines of different characters, sleeve and switching relays in said toll trunk energized upon connection of the toll trunk with a common battery line, a source of battery supply, a bridging relay bridged across the toll trunk conductors when said switching relay. is energized to connect said battery source with the trunk when said trunk is connected to a common battery line, and when said trunk is connected to a magneto line said switch ing and bridging relays remain inert whereby said battery source is not connected to the trunk circuit. 7

6. A toll trunk circuit comprising outgoing and incoming terminals, sleeve and switching relays at the incoming end of the trunk circuit said sleeve and switching relays cnergized when said trunk circuit is connected to a common battery line, a bridging relay said bridging relay being bridged across the trunk V conductors when said switching relay energizes, a bridging cutoil' relay, and means actuated when ringing current is impressed upon the line to enerring-through universal toll trunlc gize the said bridging cut-oii' relay to open the circuit of said bridging relay to prevent said relay from operating during the ringing operation.

7. A telephone system comprising local battery and common battery lines, line circuits of difierent character for said lines, a universal link circuit for extending connections from a calling line to said lines as called lines, an outgoing terminal for said link circuit and an incoming terminal for said link circuit for connecting to said line circuits, inductive paths normally uniting said terminals, means for applying ringing current to said out-going terminal, and automatic means responsive to the application of ringing current for changing said inductive paths to conductive paths.

8. A telephone system comprising a plurality of lines, a link circuit for connecting to a calling one of said lines, a trunk circuit for connecting to a called one of said lines,

a pair of terminals for said trunk circuit normally united by an inductive path, means for uniting a terminal of said link circuit to one terminal of said trunk circuit for extending a call in the direction of the called line, a ringing current generator associated With the said terminal of the link circuit for applying ringing current to the called line, and means responsive to the application of ringing current to the trunk circuit for automatically substituting a conductive path in place of the said inductive path so that the ringing current is conductively connected to the line circuit of the called line.

9. In a telephone system, a called subscribers line, alink circuit provided With a calling terminal, a trunk circuit provided With a pair of terminals and having an inductive path normally connecting said terminals, a ringing current generator associated With the terminal of said link circuit, means for connecting the terminal of said link circuit to a terminal of said trunk circuit for extending a call in the direction of the called line, means for connecting the said ringing current generator to said trunk circuit for signaling the called subscriber, and automatic means responsive to said connection for substituting a conductive path for said inductive path.

10. A telephone system comprising a link circuit for extending a connection from a calling line to a called line, an out-going terminal and a calling terminal for said link circuit, an inductive path normally uniting the terminals of said link circuit, means for applying ringing current to the said outgoing terminal, and means responsive to the application of ringing current for replacing the said inductive path by a conductive path.

11. In a telephone system, a trunk circuit provided with an outgoing terminal and an incoming terminal, a pair of strands normally uniting said terminals, impedance elements normally connected in said strands, means for applying ringing current to the outgoing terminal of said trunk circuit, and automatic means responsive to the application of ringing current for shunting the said impedance elements.

Signed by me at Chicago, county of Cook, and State of Illinois, in the presence of two Witnesses.

CHARLES S. WINSTON.

Witnesses:

G. E. MUELLER, B. OBRIEN.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents,

Washington,D C. 

